Hermetically sealed refrigerating machine



Oct. 27, 1964 K. ROELSGAARD 3,154,245

HERMETICALLY SEALED REFRIGERATING MACHINE Filed Feb. 26, 1962 United States Patent 3,154,245 IERME'IZCALLY SEALED REFRIGERATENG MACHHNE Knnd Roelsgaard, Nordborg, Denmark, assignor to Danfoss ved ing. M. Qlausen, Nordhorg, Denmark, 2 company of Denmark Filed Feb. 26, 1962, Ser. No. 175,561 Claims priority, application Germany, Feb. 24, 1961, D 35,482 Claims. (Cl. 230-432) This invention relates to a hermetically-sealed refrigerating machine of the type in which the pressure silencer or mufller is disposed in the interior of the capsule and in which the interior cavity of the capsule is under suction pressure.

A major problem in hermetically-enclosed refrigerating machines is the heat which tends to be produced interiorly of the hermetically-sealed capsule which encloses the compressor assembly. This heat is the result of heat emission from the electric motor, the heat of compression of the gas, and the heat of friction in the moving parts of the compressor.

A particularly significant cause of such heating is the compressed refrigerant and this heat must be prevented from accumulating in the capsule. Such heat is a particular problem in the case of small, modern refrigerating machines which, due to requirements for a low noise level, are spring-mounted inside the capsule and thus have very poor thermal connection to the wall of the capsule.

An increased temperature thus tends to prevail inside the capsule, and this temperature is not only harmful to the electrical parts of the compressor, but it also reduces the viscosity of the lubricant to a considerable extent. In addition, the refrigerant drawn into the compressor is superheated by reason of the increased temperature inside the capsule, and the efficiency of the compressor is thus reduced. It has previously been suggested to attack the problem of removing this heat by secondary precautions, such as increasing heat-transfer, e.g. by means of oil-coolers disposed outside the capsule, or by atomizing the oil and causing the atomized oil to condense on the wall of the capsule. A double-walled capsule, the underpart of which forms a condenser, is also known. However, these means for removing heat are complicated and they create diificulties in construction, particularly when a compact unit is desired, and they involve substantially increased manufacturing costs.

It has been proposed to provide the parts disposed inside the capsule, which carry the refrigerant under evaporating pressure, with means which restrict heat-transfer. For example, the pressure muffler or silencer is connected in the pressure line and is provided exteriorly with heat insulation and/ or with means which hinder gas flow or the deposit of oil which would tend to transfer heat. A considerable part of the heat content of the compressed refrigerant is, in this manner, prevented from being transmitted into the interior of the capsule, and heating of the unit is thus reduced.

It is an object of the present invention to provide a novel construction in a hermetically-sealed refrigerating machine to efiect a corresponding reduction of heat in the interior of the capsule.

According to the invention, a reduction of temperature int riorly of the capsule is achieved by a re-arrangement of the parts of the compressor assembly.

More particularly, in accordance with the invention, the desired heat reduction is obtained by placing the muffier or silencer in the pressure line in a position such that it will be sheltered by the other parts of the refrigerating unit, thus protecting the muilier from oil sprays.

The specific means for limiting heat-transfer provided EJ5 2245 Patented @et. 27, 19%4 "ice by the above-mentioned prior proposal is replaced, according to the present invention, by a novel positioning of the pressure muffler and, additional elements are generally not necessary to obtain the desired protection against oil sprays. However, it is preferred and has been found to be generally advantageous to provide the pressure mufiler with a special shield or to dispose the existing parts of the unit in such manner that they provide effective shie ding of the pressure muiiler. Thus, it is of advantage to place one or more suction mufilers on the cylinder of the compressor in such a position that they form a shield for the pressure muifier.

Some atomizing oi the oil takes place in nearly all refrigerating machines due to the fact that the oil from the oil-sump, after being guided to the points to be lubricated will finally be thrown out with a certain speed, or due to the fact that a special ejecting device may have been provided for the specific purpose of throwing the oil against the capsule wall for cooling purposes, or due to the fact that parts or" the unit dip into the oil-sump, thus atomizing the oil. The sheltering which is provided in accordance with this invention is thus intended to comprise the shielding of the pressure mufiler so that it is kept free of the direct influence of these oil particles.

it has been discovered that, surprisingly, much less heating of the engine, compared with previously-known constructions, takes place as a result of the placing of the pressure mother in the pressure line in a sheltered posi tion. This is due to the fact that the atomized oil is prevented from continuously spraying the pressure mufiler and thus transferring the heat in the mufller to the interior of the capsule. By disposing the mutlier in the pressure line and by shielding it a direct heat transfer is almost completely avoided.

The gas flowing through the suction chamber interiorly of the capsule and carrying suspended particles of oil can transfer heat. However, even this slight heat transfer can be reduced considerably if the pressure mufder is disposed in such manner that the pressure mufller is substantially outside the area of flow of the suction gas present inside the capsule.

Further characteristics of the invention will appear from the following detailed description of an illustrative embodiment thereof, taken in connection with the accompanying drawing which shows, in longitudinal section, a hermetically-sealed refrigerating machine embodying features of the present invention.

Referring to the drawing, the compressor, indicated generally at 1, is mounted by means of springs 4 interiorly of the capsule 2 which has a cooperating cover 3 to provide a hermetically-sealed enclosure. Springs 4 are fastened to the supporting element 5 of the motor stator, and element 5 is provided with a bearing (not shown) for the vertical motor-crankshaft 6. Shaft 6 carries the rotor for the motor, only the stator 7 of which is shown. On top of the supporting element 5 is mounted the cylinder 8 in which the piston 9 reciprocates. The piston 9 is driven, through a Scotch yoke 18, by the crankpin 11, in known manner, and at the upper dead center position of the piston or compression zone of the cylinder there is provided an intermediate valve plate 12 containing the suctionand pressure-valves, which are not shown since they are of known construction and form no part of the present invention. Both valve chambers are located in the closing plate 13 of the cylinder 8. Advantageously, a suction muiiler 1d, shown by dotted lines, can be mounted on the cylinder.

From the pressure-outletof the closing plate 13 a tube 15 leads to the pressure muffler 16 which, by means of a connecting line 17 is connected to a sinuous conduit section 18. In this manner, the pressure line can easily equalize any movements occurring between the cylinder and the point of passage of the pressure line through the wall of the capsule. This passage is not shown but is located behind the cylinder 8. The sucked-in gas is carried to the interior of the capsule through the inlet 19 and continues, through an inlet line which is not shown in order to avoid unnecessary complication of the drawing, to a valve chamber in the closing plate 13, or to a suction muffler connected to the valve chamber.

From the oil-sump 2%, oil is guided in known manner to the bearing of the rotor and to the crankpin by means of a centrifugal pump device, illustrated diagrammatically at 21 and, for example, by a helical feeding groove (not shown). In this connection, reference is made to the lubricating system shown in my application filed November 13, 1961, and entitled Lubricating Device for a Motor Compressor. Upon rotation of the shaft 6, the oil flows out at points A and B. The oil is ejected in these areas due to centrifugal action, even when no special ejecting devices are provided. The ejecting effect is further increased by the action of the counterweight 22 carried by the crankshaft 6. In accordance with the invention, the pressure muffler 15 is disposed in such manner that it can be hit neither by the oil particles ejected at A nor by the oil particles ejected at B. It is sheltered from the area or range of emission of oil at A by the supporting element of the stator, especially the free end 23. It is sheltered from the area or range of emission of oil at B by the cylinder 8, and by the suction muffiers 14 when present upon the cylinder. If the shielding by the foregoing provisions should not be as completely suificient as desired, due to the circular form of the parts and 8, shielding plate 24, indicated on the drawing by a broken line, is advantageously mounted adjacent the pressure mufiier 16.

Since the gas drawn into the capsule through the inlet 19 is lead into the upper part of the capsule and from there into the cylinder, the flow of suction gas will take place chiefly horizontally in the upper part of a capsule, and thus the pressure mufiler 16 will be located outside the area of flow of this suction gas.

The principle of the present invention can be utilized not only in connection with refrigerant compressors but Wherever a reduction in the temperature inside the capsule of an enclosed motor compressor unit is required, for example in air compressors for paint spraying units, air compressors for auto repair shops, as Well as all other gas compressors. In all of these cases, an increase in capacity and an improvement in the lubrication of the shaft bearing can be obtained in relation to known compressor constructions.

The motor and the compressor per se are not part of the present invention and they can be of conventional construction, subject to the structural changes relating to heat removal described and illustrated which are characteristic of the present invention. A typical motor compressor in which the present invention can be embodied is described, for example, in U.S. Patent No. 2,312,596. The motor and compressor can also be, for example, of the construction shown in my above-mentioned application filed November 13, 1961, entitled Lubricating Device for a Motor'Compressor.

It will also be understood that various changes and modifications may be made in the embodiments described above and illustrated in the drawing without departing from the scope of the invention as defined in the appended claims.

It is intended, therefore, that all matter contained in the foregoing description and in the drawing shall be interpreted as illustrative only and not as limitative ofthe invention.

,I claim:

.1. In a hermetically-sealed refrigerating machine of the type comprising a hermetically-sealed capsule adapted to be placed under suction pressure having an inlet for refrigeration to be drawn into said capsule and containing a compressor unit comprising means defining a cylinder and having a pressure line leading therefrom and containing a piston reciprocable in said cylinder, a driving means for reciprocating said piston in said cylinder, means defining an oil sump adapted to contain a quantity of lubricating oil, means connected to said driving means for forming lubricating oil sprays from the oil in said pump to lubricate said driving means and said piston, the combination of a pressure mufiier disposed in the interior of said capsule in an area remote from said oil sump and from said compressor unit, said mufller being disposed connected in said pressure line leading from said cylinder for receiving refrigerant after compression in said compressor unit and being positioned in spaced relation with respect to said cylinder and the other component of said machine, and said pressure mufiler being sheltered from said oil sprays produced by said spray-forming means by said cylinder and other components of the machine.

2. In a hermetically-sealed refrigerating machine of the type comprising a hermetically-sealed capsule adapted to be placed under suction pressure having an inlet for refrigerant to be drawn into said capsule and containing a compressor unit comprising means defining a cylinder and having a pressure line leading therefrom and containing a piston reciprocable in said cylinder, a driving means for reciprocating said piston in said cylinder, means defining an oil sump adapted to contain a quantity of lubricating oil, means connected to said driving means for forming lubricating oil sprays from the oil in said sump to lubricate said driving means and said piston, the combination of a pressure mutfier disposed in the interior of said capsule in an area remote from said oil sump and from said compressor unit, said mufiler being disposed connected in said pressure line leading from said cylinder for receiving refrigerant after compression in said compressor unit and being positioned in spaced relation with respect to said cylinder and the other components of said machine, said' pressure muffler being sheltered from said oil sprays produced by said spray-forming means by said cylinder and other components of the machine, said cylinder having a compression zone, and said pressure mufller being disposed close but spaced from said compression zone.

3. In a hermetically-sealed refrigerating machine of the type comprising a hermetically-sealed capsule adapted to be placed under suction pressure having an inlet for refrigerant to be drawn into said capsule and containing a compressor unit comprising means defining a cylinder and having a pressure line leading therefrom and containing a piston reciprocable in said cylinder, a driving means comprising an electric motor for reciprocating said piston in said cylinder, means defining an oil sump adapted to contain a quantity of lubricating oil, means connected to said driving means for forming lubricating oil sprays from the oil in said sump to lubricate said driving means and said piston to the combination of a pressure mufiler disposed in the interior of said capsule in an area remote from said oil sump and from said compressor unit, said mufiler being disposed connected to said pressure line leading from said cylinder for receiving refrigerant after compression in said compressor unit and being positioned in spaced relation with respect to said cylinder and the other components of said machine, said pressure muffler being sheltered from said oil sprays produced by said spray-forming means by said cylinder and other components of the machine, said cylinder having a compression zone, said pressure mufiler being disposed close but spaced from said compression zone and adjacent said electric motor.

4. In a hermetically-sealed refrigerating machine of the type comprising a hermetically-sealed capsule adapted to be placed under suction pressure having an inlet for refrigerant to be drawn into said capsule and containing a compressor unit comprising means defining a cylinder and having a pressure line leading therefrom and containing a piston reciprocable in said cylinder, a driving means comprising an electric motor for reciprocating said piston in said cylinder, means defining an oil sump adapted to contain a quantity of lubricating oil, means connected to said driving means for forming lubricating oil sprays from the oil in said sump to lubricate said driving means and said piston, the combination of a pressure mufiier disposed in the interior of said capsule in an area remote from said oil sump and from said compressor unit, said muffler being disposed connected in said pressure line leading from said cylinder for receiving refrigerant after compression in said compressor unit and being positioned in spaced relation with respect to said cylinder and the other components of said machine, said pressure muffler being sheltered from said oil sprays produced by said spray-forming means by said cylinder and other components of the machine, said cylinder having a compression zone, said pressure mufller being disposed close but spaced from said compression zone, said pressure line having a major length thereof disposed above said electric motor, and said major length thereof being remote from said muffler.

5. In a hermetically-sealed refrigerating machine of the type comprising a hermetically-sealed capsule adapted to be placed under suction pressure having an inlet for refrigerant to be drawn into said capsule and containing a compressor unit comprising means defining a cylinder and having a pressure line leading therefrom and containing a piston reciprocable in said cylinder, 2. driving means for reciprocating said piston in said cylinder, means defining an oil sump adapted to contain a quantity of lubricating oil, means connected to said driving means for forming lubricating oil sprays from the oil in said pump to lubricate said driving means and said piston, the combination of a pressure mufiler disposed in the interior of said capsule in an area remote from said oil sump and from said compressor unit, said muflier being disposed connected in said pressure line leading from said cylinder for receiving refrigerant after compression in said compressor unit and being positioned in spaced relation with respect to said cylinder and the other components of said machine, said pressure mufiier being sheltered from said oil sprays produced by said spray-forming means by said cylinder and other components of the machine, said cylinder having a compression zone, said pressure mufiler being disposed close but spaced from said compression zone, and a shield on said muffler shielding it from oil spray to preclude any contact between oil spray and said pressure mufiler.

References Cited by the Examiner UNITED STATES PATENTS 2,174,536 10/39 Smith 230232 X 2,178,811 11/39 Sateren 25058 2,200,222 5/ Tarleton 230232 X 2,274,942 3/42 Touborg 230-58 2,587,246 2/52 Touborg 23058 2,823,850 2/58 Hintze 230-232 X 2,996,240 8/51 Stocklein et al 23058 X LAURENCE V. EFNER, Primary Examiner.

ROBERT M. WALKER, Examiner. 

1. IN A HERMETICALLY-SEALED REFRIGERATING MACHINE OF THE TYPE COMPRISING A HERMETICALLY-SEALED CAPSULE ADAPTED TO BE PLACED UNDER SUCTION PRESSURE HAVING AN INLET FOR REFRIGERATION TO BE DRAWN INTO SAID CAPSULE AND CONTAINING A COMPRESSOR UNIT COMPRISING MEANS DEFINING A CYLINDER AND HAVING A PRESSURE LINE LEADING THEREFROM AND CONTAINING A PISTON RECIPROCABLE IN SAID CYLINDER, A DRIVING MEANS FOR RECIPROCATING SAID PISTON IN SAID CYLINDER, MEANS DEFINING AN OIL SUMP ADAPTED TO CONTAIN A QUANTITY OF LUBRICATING OIL, MEANS CONNECTED TO SAID DRIVING MEANS FOR FORMING LUBRICATING OIL SPRAYS FROM THE OIL IN SAID PUMP TO LUBRICATE SAID DRIVING MEANS AND SAID PISTON, THE COMBINATION OF A PRESSURE MUFFLER DISPOSED IN THE INTERIOR OF SAID CAPSULE IN AN AREA REMOTE FROM SAID OIL SUMP AND FROM SAID COMPRESSOR UNIT, SAID MUFFLER BEING DISPOSED CONNECTED IN SAID PRESSURE LINE LEADING FROM SAID CYLINDER FOR RECEIVING REFRIGERANT AFTER COMPRESSION IN SAID COMPRESSOR UNIT AND BEING POSITIONED IN SPACED RELATION WITH RESPECT TO SAID CYLINDER AND THE OTHER COMPONENT OF SAID MACHINE, AND SAID PRESSURE MUFFLER BEING SHELTERED FROM SAID OIL SPRAYS PRODUCED BY SAID SPRAY-FORMING MEANS BY SAID CYLINDER AND OTHER COMPONENTS OF THE MACHINE. 